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/*=========================================================================
Program: Visualization Toolkit
Module: vtkShepardKernel.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
/**
* @class vtkShepardKernel
* @brief a Shepard method interpolation kernel
*
*
* vtkShepardKernel is an interpolation kernel that uses the method of
* Shepard to perform interpolation. The weights are computed as 1/r^p, where
* r is the distance to a neighbor point within the kernel radius R; and p
* (the power parameter) is a positive exponent (typically p=2).
*
* @warning
* The weights are normalized sp that SUM(Wi) = 1. If a neighbor point p
* precisely lies on the point to be interpolated, then the interpolated
* point takes on the values associated with p.
*
* @sa
* vtkPointInterpolator vtkPointInterpolator2D vtkInterpolationKernel
* vtkGaussianKernel vtkSPHKernel vtkShepardKernel
*/
#ifndef vtkShepardKernel_h
#define vtkShepardKernel_h
#include "vtkFiltersPointsModule.h" // For export macro
#include "vtkGeneralizedKernel.h"
class vtkIdList;
class vtkDoubleArray;
class VTKFILTERSPOINTS_EXPORT vtkShepardKernel : public vtkGeneralizedKernel
{
public:
//@{
/**
* Standard methods for instantiation, obtaining type information, and printing.
*/
static vtkShepardKernel* New();
vtkTypeMacro(vtkShepardKernel, vtkGeneralizedKernel);
void PrintSelf(ostream& os, vtkIndent indent) override;
//@}
// Re-use any superclass signatures that we don't override.
using vtkGeneralizedKernel::ComputeWeights;
/**
* Given a point x, a list of basis points pIds, and a probability
* weighting function prob, compute interpolation weights associated with
* these basis points. Note that basis points list pIds, the probability
* weighting prob, and the weights array are provided by the caller of the
* method, and may be dynamically resized as necessary. The method returns
* the number of weights (pIds may be resized in some cases). Typically
* this method is called after ComputeBasis(), although advanced users can
* invoke ComputeWeights() and provide the interpolation basis points pIds
* directly. The probably weighting prob are numbers 0<=prob<=1 which are
* multiplied against the interpolation weights before normalization. They
* are estimates of local confidence of weights. The prob may be nullptr in
* which all probabilities are considered =1.
*/
vtkIdType ComputeWeights(
double x[3], vtkIdList* pIds, vtkDoubleArray* prob, vtkDoubleArray* weights) override;
//@{
/**
* Set / Get the power parameter p. By default p=2. Values (which must be
* a positive, real value) != 2 may affect performance significantly.
*/
vtkSetClampMacro(PowerParameter, double, 0.001, 100);
vtkGetMacro(PowerParameter, double);
//@}
protected:
vtkShepardKernel();
~vtkShepardKernel() override;
// The exponent of the weights, =2 by default (l2 norm)
double PowerParameter;
private:
vtkShepardKernel(const vtkShepardKernel&) = delete;
void operator=(const vtkShepardKernel&) = delete;
};
#endif